Serena Williams of the U.S. reacts after missing a point against Maria Sharapova of Russia in her semifinal match during the Brisbane International tennis tournament in Brisbane, Australia, Friday, Jan. 3, 2014. (AP Photo/Tertius Pickard)

The defending champion will play second-seeded Victoria Azarenka in Saturday's final, and will be favored to retain the title that kicked off her stunning 2013 season that included 78 wins from 82 matches and 11 titles.

After blowing two match points in the tiebreaker, Williams sealed the win with her seventh ace against the third-seeded Sharapova.

In their first meeting since the French Open final, the uneasy rivals barely exchanged glances before the match and only briefly shook hands after.

Both players were returning aggressively — leading to 15 double-faults between them and six breaks of serve in the second set — and hitting their grounds strokes hard and deep. Williams hit consecutive double-faults to give Sharapova a mini-break at 5-4 in the tiebreaker, something she said she couldn't remember ever doing before on tour. Sharapova responded with a double-fault to make it 5-5, and said she'd missed her opportunities.

"I had a few missed chances ... but overall I'm happy I can compete at this level in my third match back," Sharapova said. "It's a good sign for me."

Any friendship that existed between the pair soured when they traded personal barbs relating to their romantic relationships ahead of last year's Wimbledon, where Sharapova made an early exit.

Sharapova only played one match after that in 2013 as she recovered from a right shoulder problem.

Williams said she'd need to vastly improve her first-serve percentage — which sunk to 40 in the semifinals — to beat Australian Open champion Azarenka, who overcame a shaky serve and another case of the nerves to beat former No. 1-ranked Jelena Jankovic 1-6, 6-3, 6-4.

Facing two of her biggest rivals back-to-back in her first tournament of the year, and less than two weeks before the Australian Open, is a big step up in preparations for Williams.

"Yeah, I feel like I'm being pushed into the deep end straightaway," she said. "I also think it's a good thing."